The present invention relates to generators and, more particularly, to an enclosure for a generator rotor.
In a conventional generator having a rotor and a stator, the rotor is provided with field windings that excite the generator while receiving a current from an exciting current source. The stator is provided with armature windings from which electrical power is output. Typical rotor construction requires that a field winding be assembled bar by bar, into radial slots milled into a rotor forging. Containment of the rotor field windings is typically achieved using rotor wedges, rotor teeth and retaining rings.
It would be desirable to replace the bar by bar assembly with a solid rotor having parallel slots milled into a rotor forging. With this structure, the containment components could be replaced with a simplified enclosure.
In an exemplary embodiment of the invention, an enclosure for a rotor in a generator including the rotor and a stator is comprised of a non-metallic tube. The tube may be formed of a plurality of rings that are spaced at predetermined intervals or of a continuous tube including ventilation holes therein. The rings are spaced axially such that cross slots in the rotor lie between the rings. These cross slots provide corrections to dissymmetry in rotor stiffness around a periphery of the rotor. The spaces between adjacent rings provide discharge openings for winding ventilation without introducing stress concentrations in the enclosure. Preferably, the non-metallic tube is formed of a low density composite material, such as a carbon fiberxe2x80x94glass fiber epoxy composite.
In another exemplary embodiment of the invention, a rotor in a generator includes a magnetic core having at least two poles, a plurality of winding assemblies, one for each pole, and an enclosure housing the core and the winding assemblies, wherein the enclosure is comprised of a non-metallic tube.